This grant focuses on the role of the chemokine receptors: CCR6 and CCR10 in cutaneous immunity using receptor knockout/GFP-knock-in mouse models. The CCR6N receptor has been localized on a subset of CD4 T-cells, most B-cells and a subset of dendritic cells including epidermal Langerhans cells. A chemotactic gradient of MIP-3a, the unique chemokine ligand for CCR6, may participate in the recruitment of Langerhans cell precursors to the skin. A CCR6 knockout/GFP reporter knock-in mouse mode was recently established in the lab. This mouse model will be used to establish the role of cytokine-mediated signaling in the regulation of CCR6 expression in dendritic precursor cells and to establish whether functional Langerhans cells residue in the epidermis of CCR6 deficient mice. CCR10 is the only known receptor for the chemokine CCL27 (CTACK), which is selectively made by keratinocytes. CCR10 is expressed on a subset of T cells, Langerhans cells, melanocytes, dermal fibroblasts, and microvascular endothelial cells, strongly suggesting a role for CCR10 in skin function, not limited to cutaneous immunity. To better understand the role of CCR10 in cutaneous biology, I plan to generate a CCR10 knockout/GFP knock-in mouse using a strategy similar to that used to make the existing CCR6 mutant, The CCR10 GFP knock-in mouse will be used to study the pattern of distribution and regulation of CCR10 expression in both the leukocytes and other resident skin cells. A neutralizing rat-anti-mouse CCR10 monoclonal antibody will be made to test the effects of interrupting chemokine signaling through CCR10. CCR10 knockout mice will be characterized to determine if absence of CCR10 leads to developmental abnormalities in skin and whether CCR10 is required for effective cutaneous immunity.